bastige

No knife hitting the paint for any reason here, I'd like to see a better pic of the damage as it doesn't even look bad from what I think I'm seeing  Were child seats involved  Did you move your girlfriend/boyfriend recently  Nobody has the time or wants to look like it's a repeat problem and take the time to document every tiny thing they find with pictures, unless they've overbooked you to check in Cameron's dads Ferrari.   I've been accused of some stupid  in my day so I'm on the defensive here for ma fellow tinter. 

Your said what.    "4 days prior I prepared by taking pics of all the windows and paint areas around them in case there were scratches/damage after tinting."" NO ONE DOES THIS."
You sound like the guy that eats 90% of his meal and complains to get a free meal. I wonder if your yelp reviews are 70% 1 stars and 30% 2 stars.
Dude!!  4 days before you take pics predicting this would happen. Ive seen this before and pisses me off that people try this. Now!  if you had 4k video in front of the shop that same day 5 mins before handing over the keys. You might have a case. Remember your in snow territory. Your car probably has marks everywhere.
Once your car leaves the shop your done. How can you 100% say it was them" You can't" 
Thats like blaming someone for stealing your wallet and later on you find your wallet. You end up feeling really stupid and bad about it. 
I believe we know what really happened

Although the installer was a dick, he refunded the total cost which was more than the repair and none of us know how many scratches were on what year car that we never saw, who knows if this customer was wrong or right without pics? 
I think the customer handled it right. The business owner, although unnecessarily nasty, obviously doesn't think he did it but still satisfied the customers wishes and took a loss to do it.
I think it's worthy of no review, good or bad. My 2 cents on it

Sounds fishy the guy would take all those pics before the job, so he knew he’d have some ammo for after the job was finished. I don’t buy it at all. In the end, he got a free tint job and will never get the scratch fixed. If he posted pics we could all tell if the scratch was from the installer. I feel like this isn’t his first rodeo. Probably eats all of his dinner, then complains that it was no good to get it comp’d.

And it's very important that people with your experience leave negative ones imo. 

Call the shop. Tell them you have a slight issue and you would like to schedule a time for someone to look over the vehicle. Bring the car and your pictures back to the shop. Tell them your issue. Allow them a chance to rectify the matter. If it was darker than permitted by law in your state, that’s likely why there wasn’t a warranty card given. If it is legal shading, then ask for the warranty card and written receipt. If they’re a professional shop, they will do what they can to make it right. 

They can only “prove” it by letting you look inside the film core prior to the film’s installation. And then allowing you to watch the entire job. Not many shops do that. But that’s the only way, and even then an unscrupulous person can swap out the core labels. You just have to find a shop you can trust. 
 
As far as the scratch; as professionals we carry insurance. But most of the time it’s just easier to pay someone to fix the damage out of our pocket rather than make a claim. Sometimes the deductible is higher than the cost of the repair. Remember, we’re humans installing plastic on your glass. Accidents happen. What makes a shop truly professional is avoiding those accidents, but rectifying them if they do happen.